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  • Writer's pictureBrandant Robinson

DRO Mill Upgrade

For some time now I've wanted to upgrade my Harbor Freight Mini Mill with a digital readout system. These low-end mills have a lot of backlash in the lead screws and the dials on the feed wheels are also somewhat questionable and very cumbersome to use. You can certainly work with the machine as it comes from the factory, but to get the accuracy that I really need for a couple of upcoming projects I really wanted the added accuracy and convenience that a DRO system would provide. So, after doing some research, I placed my order for a set of iGaging DROs for all three axes.

Here's the mill with the DRO system installed on all three axes. I mounted the readouts back out of the way on a swivel arm so I can swing them out of the way to get to my tooling behind.

Here is what the DRO looks like out of the box. This one is the 24 inch one that will be used on the Z axis. They are a lot like a digital caliper with the sensor which slides up and down a bar.

Here's the Z-axis installed on the column. I had to manufacture a pair of standoffs so that the bar would clear the mill components. I also had to build a mounting bracket that would attach the DRO to the mill head. I used some scrap aluminum that I had lying around from the surface grinder project.

The Y-axis was fairly simple to install. I mounted the bar directly to the body of the mill and modified one of the brackets that came with the DRO to connect it to the saddle.

The X-axis was the most challenging of the three. I had to completely disassemble the table and saddle in order to get the DRO mounted on the back side of the bed where it needed to be. Having everything apart did give me an excuse to do a thorough cleaning of the mill and to adjust the X and Y gibs.

I put the new DRO system through its paces, and everything seems to be functioning properly. The readout is a little slow to display, so I'll have to adjust the feed rate down a little when I approach the final destination. That's certainly something I can live with. All in all, I'm quite please with this new upgrade. I can't wait to use it on an actual project. I hope to start a new build next week, so hopefully I'll get to give it a go then.

- Brandant Robinson

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